feat: Enhance admin announcement functionality and introduce PWA installation prompt

- Update sendAdminAnnouncement to support multiple configured admin pubkeys and improve console output for clarity.
- Add new script send_posts_from_configured_admins.js to send posts from multiple admins for testing purposes.
- Implement PWAInstallPrompt component to guide users in installing the app, including handling installation status and browser compatibility.
- Integrate PWAInstallPrompt into Home.vue for improved user experience.

src/pages/Home.vue

@@ -1,5 +1,6 @@
 <template>
   <div class="container py-8 space-y-6">
+    <PWAInstallPrompt auto-show />
     <NotificationPermission auto-show />
     <NostrFeed feed-type="announcements" />
   </div>
@@ -8,4 +9,5 @@
 <script setup lang="ts">
 import NostrFeed from '@/components/nostr/NostrFeed.vue'
 import NotificationPermission from '@/components/notifications/NotificationPermission.vue'
+import PWAInstallPrompt from '@/components/pwa/PWAInstallPrompt.vue'
 </script>